From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Fri, 31 Mar 2006 10:41:56 +1000 From: 'David Gibson' Subject: Re: [patch] don't allow free hugetlb count fall below reserved count Message-ID: <20060331004156.GK19421@localhost.localdomain> References: <200603310013.k2V0Dng26534@unix-os.sc.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <200603310013.k2V0Dng26534@unix-os.sc.intel.com> Sender: owner-linux-mm@kvack.org Return-Path: To: "Chen, Kenneth W" Cc: linux-mm@kvack.org, akpm@osdl.org List-ID: On Thu, Mar 30, 2006 at 04:14:34PM -0800, Chen, Kenneth W wrote: > With strict page reservation, I think kernel should enforce number of > free hugetlb page don't fall below reserved count. Currently it is > possible in the sysctl path. Add proper check in sysctl to disallow > that. Hmm.. maybe. I have no strong view either way. With this patch you're safer against accidentally taking hugepages away from a process which needs them. On the other hand, leaving it out gives a sysadmin more flexibility to free up normal memory at the expense of risking crashes for hugepage processes. Ken - did you keep working on your alternative strict reservation patches? Last I recall they seemed to be converging on mine in all the points I thought really mattered, except that I hadn't updated mine to remove some of the problems you pointed out in it while developing your patches (e.g. unnecessarily taking a lock on reserve). I'm actually on a very long leave at the moment, so I'm not really doing anything active. Those problems should be fixed at some point, though, either with patches to my approach, or by replacing it with yours. > Signed-off-by: Ken Chen > > --- ./mm/hugetlb.c.orig 2006-03-30 15:32:20.000000000 -0800 > +++ ./mm/hugetlb.c 2006-03-30 15:48:22.000000000 -0800 > @@ -334,6 +334,7 @@ > return nr_huge_pages; > > spin_lock(&hugetlb_lock); > + count = max(count, reserved_huge_pages); > try_to_free_low(count); > while (count < nr_huge_pages) { > struct page *page = dequeue_huge_page(NULL, 0); > -- David Gibson | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_ | _way_ _around_! http://www.ozlabs.org/~dgibson -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org